Solar cell panels are arranged on the roof of a sunny building, or some other in the state of being connected in large numbers to each other in order to increase the electric power generated therefrom. About each of the solar cell panels, a terminal box is fitted to the rear surface thereof. The terminal boxes of any adjacent two of the solar cell panels are electrically connected to each other through an external connection cable.
A conventional solar cell panel generally has a structure wherein a solar cell is sealed up between a light-transmitting front-surface member and a non-light-transmitting rear-surface member with a bonding sealing agent or some other. An electric current generated from the solar cell is transmitted to both poles of a terminal plate of the terminal box, which is set on the rear surface, through a bus bar led out, into a perpendicular direction, from a hole made at a substantially central position of the rear-surface member (See Patent Document 1).
In recent years, suggestions have been made about solar cell panels which have a front-surface member and a rear-surface member each made of a light-transmitting material. In order to make good use of, for example, a space on the rooftop of a building, the solar cell panels are set perpendicularly to the periphery of the rooftop, thereby functioning also as a fence (separator). In this way, the panels are harmonized with the scenery. About the solar cell panels, both of their front surface and their rear surface can receive light from early morning to evening. Thus, the panels are suitable for a case where electric power generation having a flat property is desired to be obtained. FIG. 1 illustrates a schematic sectional view of the structure of any one of the solar cell panels. In FIG. 1, reference number 1 represents a solar cell panel; 2, a front-surface member which constitutes the front surface side of the solar cell panel 1; and 3, a rear-surface member which constitutes the rear surface side thereof. These members are each made of a light-transmitting material, such as glass or a plastic material. Reference number 4 represents solar cells which each have, for example, a structure wherein a large number of solar cells made of silicon crystal, which are known in the prior art, are arranged in a matrix form; and 5, a bus bar for connecting the solar cells electrically to each other and transmitting an electric current generated from each of the solar cells 4 to both poles of a terminal plate inside its terminal box. The bus bar 5 is led out from between the light-transmitting members at an end of the solar cell panel 1 without making any hole in the rear-surface light-transmitting member. Reference number 6 represents an electrically-insulating bonding sheet for sealing up the solar cells 4 between the front-surface member 2 and the rear-surface member 3.
Conventionally, in order to fit a terminal box to such a solar cell panel, both surfaces of which are each made of a light-transmitting member, the following is adopted as illustrated in FIG. 2: a bus bar is led out from between the light-transmitting members at an end of the solar cell panel 1; subsequently, the bus bar is extended to a predetermined position of the rear surface while the bus bar is laid onto the rear-surface light-transmitting member in naked or exposed state; and then the terminal box is fitted to the panel. Since the bus bar is not wholly covered with the terminal box, the bus bar exposed to the outside is covered with an electrically-insulating sealing agent to ensure the waterproofness of the bus bar.
However, a solar cell module composed of solar cell panels and terminal boxes is exposed to an outdoor environment that undergoes heavy changes over long years. Thus, the above-mentioned conventional terminal-box-fitting method has problems that the bus bar is made naked by the secular changes, water invades the terminal boxes from bus bar-intakes in the terminal boxes, and the terminal boxes drop off from the solar cell panel.